I like Shoei. I own 2 an RF 1000 and X-11
I mainly use my X-11. I really like it. It's light and does an excellent job cutting wind noise. It was also their top of the line helmet until the X12 came, so it's pro kit, makes me feel cool. You can also remove the lining to clean it, that is also a big plus.
The RF 1000 is good quality, but not as good as the X-11. It's still a nice, expensive helmet, but it doesn't have as many vents, and the lining is non-removable. It also doesn't fit as well, and leaves a bruise on my forehead if I wear it for a long time. I keep it as a spare, comes in handy of I want to take a girl for a spin. It's also good to have a back-up if my other helmet is damaged.
That said, I would never buy a used helmet. If you can't afford a new Shoei, look for one on closeout. Failing that, pick up a less expensive helmet like a Scorpion or HJC. No matter how good the helmet is, manufacturers recommend you discard and replace a helmet that was involved in an impact. You don't know what the previous owner has done with that one. At the end of the day, they're all just made out of styrofoam anyway.